Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressor compresses air drawn into the engine and delivers high pressure air to the combustor. In the combustor, fuel is mixed with the high pressure air and ignited. Products of the combustion reaction in the combustor are directed into the turbine where work is extracted to drive the compressor and, sometimes, an output shaft, fan, or propeller. Left-over products of the combustion reaction are exhausted out of the turbine and may provide thrust in some applications.
Compressors and turbines typically include alternating stages of static vane assemblies and rotating wheel assemblies. The rotating wheel assemblies include disks carrying blades around their outer edges. When the rotating wheel assemblies turn, tips of the blades move along blade tracks included in static shrouds that are arranged around the rotating wheel assemblies. The blade tracks block gasses from passing over the blades without interaction with the blades.
Some blade tracks are formed by a number of blade track segments arranged circumferentially adjacent one another to form a hoop around the blades of the rotating wheel assemblies. An annular clearance gap may be formed between the tip of the blades and the blade track segments. A size of the clearance gap may be controlled to block gasses from passing between the blades and the blade track segments to increase the efficiency of the gas turbine engine.